Self-resetting trip-cock.



E. H. DEWSON.

SELF RESETTING TRIP COCK.

APPLICATION FILED JULY 25.1910.

' Patented Jan. 18, 1916.

TOR

THE COLUMBIA PMNOGRAPH 310., WASHINGTON, D. c.

EDWARD H. DEWSON, or new YORK, n. Y., ASSIGNOR .ro THE vvnsrinerrousn 13 BRAKE COMPANY, or PITTSBURGH, rnnnsynvnnm, A conroaarron or renn- SYLVAINIA.

SELF-RESETTING TRIP-COCK.

Specification of Letters Patent.

Patented Jan. 18, 1916.

To all whom it may concern Be it known thatl, EDWARD H. Dawson, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented new and useful Improvements in Self-litesettlngTr p- Cocks, of which the following 1s a specification.

This invention relates to trip devices and more particularly to the type adapted for use on railway trains and operating upon engagement With an obstruction along the track to vent the train pipe to efiect an appllcation of the brakes.

Trip devices upon cars often receive sudden blows, especially when the train is running at a high rate of speed, and this s apt to cause the trip to rebound from its stop with such force as to close the train pipe vent valve before a sutlicient time has elapsed to insure the desired reduction in train pipe pressure. 0 y

The principal object of my nvention is to provide a trip device having means for preventing the above undesired action.

In the accompanying drawing; Figure 1 1s a section on the line aa oi F ig. 2 of a trip device embodying my invention; Fig. 2 a section of same on the line 6-6 of Fig. l and Fig. 3 a sectional view of a modified form of a trip device embodying my improvement.

As shown in Figs. 1 and 2 of the drawing a body casting lniay be provided having an arm 2 for securing the trip device. to a suitable bracket on the railway vehicle, the arm having a slot 3 for a clamping bolt, so that the trip device may be adjusted as desired. The casting 1 has a seat 4 for a rotary valve 5, the latter being provided with a stem 6 extending through a bushed bearing in the casting 1. On the end of the stem 6 is secured a trip lever 7 adapted to engage an obstruction along the track. Opening to the seat a are preferably two oppositely arranged ports or cavities 8 Which lead to a common atmospheric exhaust port 9, and the rotary valve 5 is provided with two through ports 10 adapted to register With the ports 8 upon partial rotation of the valve 5.

A. cap casting 11 forms a casing for the rotary valve 5 and contains a valve chamber 12 having communication with the train pipe 13. Between the casing 11 and the valve 5 is mounted a spring 14 for assisting in maintaining the valve to its seat. On the cap 11 concentric with the rotary valve 5 isxa hub 15 adapted to carr a coil spring 16 provided with projecting ends, 17 adapted to normally engage fingers 18 on the rotary valve. On

the casing 11 are stops 19 also adapted to .engage the spring ends 17.

The pressure carried in the train pipe acts on the rotary valve 5 and tends to hold same to its seat with considerable frictional. re sistance by reason of the unbalanced pressure due to the large exhaust ports or cavities 8, Which are open to the atmosphere, and are much larger than the two ports, 1-0, in the valve. If the trip lever 7engages an obstruction along the track the same is operated to rotate the valve 5, one of the fingers 18 being pushed around With the valve against the resistance of the spring 16, the other end of the spring being held by the opposite fixed stop 19., The ports 10 are thus brought into register with the ports 8 so that fluid is vented from the train pipe and an application of the brakes iseifected in the Well known manner. In this open position of the vent valve, the cavity or cavitles, 8, expose a certain unbalanced area of the valve to the atmosphere, and the train pipe pressure acting on the opposite side. produces considerable frictional resistance to movement of the valve upon its seat. This serves to temporarily hold the valve in its open position, since under the normal degree of train pipe pressure, the spring, 16, is not sufiic1ently strong to overcome this frictional resistance, and thus a full application of the brakes is insured. The vent valve Will thus be held open for a time until the train pipe pressure has been reduced to a predetermined point at Which the spring is sufficient to overcome the resistance and operates to re turn the valve to its normal closed position, thus avoiding the necessity of manually closing the vent valve, and permitting the prompt release and further control of the brakes by the engineer. It Will thus be evi dent that the valve may be maintained open until the train pipe pressure has been reduced to a predetermined degree according to the resistance of the spring 16.

In some cases, the rotary valve 5 may be providedwith vanes 20 Which are so positioned that when the rotary valve is moved from either direction to its open position,

the air from the train pipe will impinge on one of the vanes 20 and thus act to maintain the valve open. I

In Fig. 3 is shown a slightly modified form of trip device in which a casing 21 is provided having a piston chamber containing a piston 22 subject on one side to pressure from train pipe 13 and on the opposite side to the pressure of a spring 23. The trip lever 2 is provided with a projecting portion 25 upon which normally rests the end of a stem 26 attached to piston 22. An atmosphere exhaust port 27 in the casing 21 is controlled by piston 22 and is normally held closed thereby. Upon engagement of the trip lever 24: with an obstruction along the track, the same is partially rotated and the stem 26 is permitted to drop down on a lower level of the trip lever, the piston 22 being forced outwardly by the train pipe pressure against the resistance of spring 23. The atmospheric port 27 is thus uncovered and air is vented from the train pipe. When the train pipe pressure has been re duced by venting through the port 27 to a degree less than the tension of spring 23,

the piston 22 is movedinwardly and the trip lever 2i is thereupon permitted to assume its normal position by gravity.

It will now be evident that my invention provides means for preventing violent oscillatory movement of the trip lever upon being struck by an obstruction, thus insuring that the desired reduction in train pipe pressure will be obtained.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is z 1. In an automatic train stop, the combination with the train brake pipe, of a trip valve device comprising a casing having a valve seat, vent valve slidably mounted thereon and held against its seat by train pipe pressure, said seat having a cavity exposing an unbalanced area of the valve to the atmosphere in its full open position for producing frictionalresistance, a trip mem- Copies of this patent may be obtained for to the atmosphere in all positions of the valve, a trip member foropening said valve, and a spring tending to return said valve to its closed position.

3. In an automatic train stop, bination with a train brake pipe, of a trip valvedevice comprising a casing having a valve seat, a rotary valve mounted thereon the oomand controlling a train pipe ventport, a trip v I member for openlng said valve, anda coiled spring mounted on a projection within the valve'chamber and having one end engaging a fixed part of the casing and the other end. engaging the valve for automatically closing the same.

l. Ina tram stopping device, the combination with a train pipe, of a trip valve device adapted to be opened by engagement with an obstruction along the track to vent air from the train pipe, and means operated by the flow of air from the train pipe through the vent port and tending to hold said trip valve in its open position.

5. In a train stopping device, the combination with a train pipe, of a trip valve device adapted to be opened by engagement with an obstruction along the track to vent air from the train pipe, and vanes mounted on the valve and subject to the flow of air from the train pipe and tending to hold said trip valve in its open position.

In testimony whereof I have hereunto set my hand.

EDWARD H. DEWSON.

Witnesses:

G120. E. BAKER, E. W. DAVIS.

Washington, D. G. 

